tests/html: removed usage of deprecated unittest features

tests/html/mutationobserver_test.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library mutationobserver_test;
 import '../../pkg/unittest/lib/unittest.dart';
 import '../../pkg/unittest/lib/html_individual_config.dart';
 import 'dart:html';
 
 // Due to https://code.google.com/p/chromium/issues/detail?id=329103
@@ skipping 33 matching lines @@
           expect(nodes.length, count);
           expect(nodes, expectation);
         }
       }
 
       // If it's not supported, don't block waiting for it.
       if (!MutationObserver.supported) {
         return () => done;
       }
 
-      return expectAsyncUntil2(callback, () => done);
+      return expectAsyncUntil(callback, () => done);
     }
 
     test('empty options is syntax error', () {
       expect(() {
         var mutationObserver = new MutationObserver(
             (mutations, observer) { expect(false, isTrue,
                 reason: 'Should not be reached'); });
         expect(() { mutationObserver.observe(document, {}); },
                throws);
       }, expectation);
@@ skipping 38 matching lines @@
         var mutationObserver = new MutationObserver(
             mutationCallback(2, orderedEquals([div1, div2])));
         mutationObserver.observe(container, childList: true, subtree: true);
 
         container.append(div1);
         div1.append(div2);
       }, expectation);
     });
   });
 }